The following periodic measurements will be made during the study: productivity and accuracy to enter a list of state populations, and a search for apostrophes (‘) in a document on one of the states of the U.S. These tasks will require 4 hours testing with each of the two pairs of trial glasses for two periods (each period lasts for one month). Subjects will be asked to return to the clinic for 4 hrs during the first 4-week period and for 4 more hrs during the second 4-week period. At each visit subjects will be asked if they have experienced any undesirable reactions and will complete a short survey.